Indoor plants are commonly used in shopping centres, hotels, and resorts to create a relaxed and pleasant atmosphere. The presence of greenery helps reduce stress, improves air quality, and enhances the aesthetic appeal of indoor spaces.
Filtering sounds (B) can be a minor benefit but is not the primary reason for indoor plants here.
Reducing glare (C) is usually achieved through blinds or curtains, not plants.
Line calligraphy (D) is unrelated to the function of indoor plants.
Therefore, indoor plants mainly contribute to creating a calming environment.